An electronic ballast is a commonly used electronic component and is widely used in the illumination field. A whole electronic ballast comprises an input rectifier module, a power factor calibrating module and a DC/AC inverter. Thus, an electronic ballast must be packed into suitable sizes to enable the use of conventional electronic ballast in household.
Chinese Utility Model No. 01256696.9 discloses a casing for electronic ballast adapted to be used in outdoors illumination devices. The middle of the case for electronic ballast is designed to be a hollow metal casing. The both ends of the casing are designed to be socket-connected with a polymer casing made with a mould. The polymer casing fits the caliber of the metal casing and is provided with a plurality of wire holes at the outside depending on the number of wires.
However, most of the currently used electronic ballast are of a two-piece or multi-piece casing configuration which comprises several mechanical components. These mechanical components comprises a base portion, a lid portion, a screw or support, an insulation plate (in case that the casing is made of metal material), and a filling portion which forms part of the overall mechanical structure and serves to hold the PCB in place inside the casing. Nevertheless, the casing for electronic ballast from prior art is assembled by a plurality of components and is structurally complicated as well as costly in manufacturing. Thus, it takes too much time to assemble the casing and electronic components, thereby further increasing the cost of the overall product.